compile broken on Java6

[Julian Reschke]

[ERROR] Failed to execute goal 
org.apache.maven.plugins:maven-compiler-plugin:2.5.1:compile 
(default-compile) on project oak-upgrade: Compilation failure
[ERROR] Failure executing javac, but could not parse the error:
[ERROR] An exception has occurred in the compiler (1.6.0_45). Please 
file a bug at the Java Developer Connection 
(http://java.sun.com/webapps/bugreport)  after checking the Bug Parade 
for duplicates. Include your program and the following diagnostic in 
your report.  Thank you.
[ERROR] com.sun.tools.javac.code.Symbol$CompletionFailure: class file 
for org.apache.felix.scr.annotations.ReferenceCardinality not found